Hundreds of thousands of opposition protesters rallied in central Beirut on Friday, in a Hezbollah-organized demonstration aimed at bringing down the government of Prime Minister Fuad Siniora. Thousands of the protesters are camped out in the street outside the prime minister's office, and say they will not move until he resigns. VOA Correspondent Challiss McDonough reports from Beirut.

The crowd was massive, overflowing two public squares in central Beirut and choking the streets leading up to them in every direction. As they came, they chanted slogans denouncing the prime minister and his government.

The demonstrators waved the Lebanese flag as a sign of unity. Hezbollah leader Hassan Nasrallah had told his followers to bring only the national flag, not the bright yellow-and-green Hezbollah banner.

For the most part, people complied. But many protesters wore Hezbollah baseball caps or t-shirts, and many others waved enormous orange flags with the checkmark logo of the Free Patriotic Movement, a Christian party led by former General Michel Aoun.

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Aoun spoke to the rally from behind bulletproof glass, to rapturous applause. His party won more seats than any other Christian party in last year's election, and one of the opposition's stated goals is forcing the government to give him seats in the cabinet. The opposition says it wants one-third of the cabinet seats, so it can veto government decisions.

In the crowd, 31-year-old lawyer and Aoun supporter Imad Geara said he believes their demands are reasonable. "We are the majority, and we're only demanding a third of the government, 33 percent of the government. And he's not ready to give us this. We were happy that the Syrians went from Lebanon. Now the Americans came in place of the Syrians. They are now, unfortunately, after Syria, the United States is governing Lebanon. And I think we will have a civil war in Lebanon if Mr. Siniora will not accept (agree) to share Lebanon with the others," he said.

Until recently, Hezbollah and Amal, the two Shi'ite opposition parties, were part of Mr. Siniora's government. But their five ministers, plus a sixth loyal to Christian President Emile Lahoud, have resigned in protest over government plans for an international tribunal to prosecute those responsible for a string of political assassinations. With no Shi'ites in the cabinet, the opposition now says the government is illegitimate.

As the protesters thronged outside, Mr. Siniora remained in his office complex, known as the Serail, along several members of his cabinet. They have been essentially living there, out of fear for their safety, ever since the minister of industry, Pierre Gemayel, was killed a week and a half ago. The opposition protests were postponed after the assassination out of fear they would spark violence.

Thursday night, on the eve of the protest, Prime Minister Siniora flatly rejected the idea of stepping down. He said Lebanon's independence and democracy are under assault.

He said, "We will not allow them to topple the democratic system or its institutions. We will not accept a state within a state. We are the legitimate and constitutional government, for all Lebanon and for all Lebanese."

Before the protest, soldiers cordoned off the government building with concertina wire and armored vehicles to keep the protesters away. As evening fell, thousands of demonstrators -- mainly from Hezbollah -- erected tents in the streets outside the building, and said they would camp there until Mr. Siniora steps down.

Wearing both a Hezbollah hat and an orange Aoun scarf, protester Issam Haraka said he is prepared to sleep in the open air for as long as it takes to bring down what he termed the "fake government." "We can't make Mr. Hassan Nasrallah's words gone with the wind. He told us go stay there. We'll stay here. It's our duty, we feel. Yeah, we'll stay here," he said.

And the protesters looked well-prepared. In addition to white canvas tents, they had portable toilets and large water tanks, apparently set for a long stay.

On the other side of the government building, a smaller but fiercer-looking crowd assembled on a darkened street, away from the demonstration. Many of those men wore white baseball caps and carried two-way radios, indicating that they were higher-level Hezbollah members, or organizers.

As night set in, some used tattered protest posters as prayer mats, saying their evening prayers alongside coils of razor wire. Others stretched out in the street, getting ready for a long, chilly night.